A rear axle in a motor vehicle rear suspension system referred to alternatively as a "trailing arm", "twist axle", or "compound crank" suspension system includes a pair of longitudinal control arms usually made of cast iron or aluminum and a transverse torsion bar usually made of steel. Each control arm has a first end hinged to a body of the motor vehicle for up and down pivotal movement and a second end at which a wheel spindle is rigidly attached. Respective ones of a pair of rear road wheels are rotatably mounted on the wheel spindles and guided in vertical suspension excursions relative to the body of the motor vehicle by the control arms. Respective ones of a pair of primary suspension springs are disposed between the control arms and the body of the motor vehicle. Commonly, the torsion bar has a channel-shaped or C-shaped cross section except at respective ones of a pair of opposite terminal ends thereof which are rolled or otherwise formed into right circular cylinders. The circular edges of the terminal ends of the torsion bar are welded to respective ones of the control arms. The torsion bar flexes resiliently in bending and in torsion in response to unequal suspension excursions of the control arms to supplement the primary suspension springs. A rear axle according to this invention is a novel alternative to the known rear axle just described.